Apparatus for eliminating bearing drag



p 1968 B. STEVENS, JR ET AL 3,401,541

APPARATUS FOR ELIMINATING BEARING DRAG Filed Nov. 30, 1955 2 Sheets-Sheet 1 A 52 55 49 so INVENTORS- BROOKS STEVENS JR. Y HAROLD R. WILCOX ATTORNEYS Sept. 17, 1968 B. STEVENS, JR.. ET 3,401,541

APPARATUS FOR ELIMINATING BEARING DRAG 2 Sheets-Sheet 2 I Filed Nov. 30, 1965 TEVENS JR.

%A\A I02 INVENTORJ- BROOKS S HAROLD R. WILCOX K &

ATTORNEYS United States Patent 0 3,401,541 APPARATUS FOR ELIMINATING BEARING DRAG Brooks Stevens, Jr., Concord, and Harold R. Wilcox, Maynard, Mass., assignors to Riggs & Lombard, Inc., Lowell, Mass., a corporation of Massachusetts Filed Nov. 30, 1965, Ser. No. 510,641 9 Claims. (Cl. 68-175) ABSTRACT OF THE DISCLOSURE Apparatus for advancing a fragile web over and under a series of rolls in a liquid dyeing tank, some of the rolls being submerged. Each submerged roll is arranged to substantially float in the liquid to reduce frictional bearing drag. Each roll is mounted in double bearings with one bearing of each double bearing driven by means of a variable speed control mechanism so that bearing drag is reduced to zero. A slight impositive forward urge is given to each roll while a slight upward and downward tension is given to the web by the Zero weight submerged rolls.

This invention relates to the transport of webs of material in continuous lengths under minimum tensions through various treating processes. It is especially applicable to materials that may alter in lengthwise dimensions during such process, or materials that have a high stretch strain ratio; and hence must be handled with lowest possible tensions.

Finishing processes of textiles offer one of the best examples. Many machines are now in use in which fabric is transported through a liquid treating process consisting of a series of tanks with the fabric arranged in festoons or loops over and under a succession of rolls with one set of rolls being above this liquid and the other below the surface. There are often a succession of tanks for different treatments and a set of squeeze or expression rolls are located between each tank, with each set of squeeze rolls individually controlled by a tension sensing device so as not to excessively tension cloth in the previous tank. The opposite arrangement may be used where the surface speed of the squeeze rolls is controlled by the accumulation of fabric immediately following the squeeze rolls.

In order to keep fabric, especially in open width, tracking properly over the various rolls, a certain minimum tension is necessary. If the various rolls above and below the liquid are not driven, there is a drag or tension produced from two causes: (a) the friction or the torque of the bearing in which the roll is mounted, and (b) the friction or drag of the liquid against the fabric.

The final tension may be excessive because this tension is not just that of the first pass times the number of passes because of the additive effect of multiple passes increasing the tension on the cloth on following rolls, resulting in additional bearing load and torque.

Various means have been adopted to overcome this. The obvious method is to drive the rolls. If these are driven at a fixed speed, then problems result if the fabric shrinks or stretches. Clutches can be employed, but cost, adjustment and maintenance do not make this a good solution. In US. Patent 2,474,717 to Belcher of June 28, 1949, the bottom rolls only are driven at a surface speed appreciably exceeding the speed of web delivery. A forward motion is given the cloth when tension tightens the cloth against each bottom roll but there can be problems of scutfing the cloth and also difiiculties in the use of stufiing boxes, with such submerged rolls.

The present invention contemplates a roll which has effectively no drag from bearing friction. The increase in the torque to turn a shaft in a bearing is less than the in- 3,401,541 Patented Sept. 17, 1968 crease of rotational speed over a wide speed range once the initial static friction has been overcome.

Now if a roll is mounted with one end in a conventional fixed bearing and the other end is mounted in a rotatable bearing of this invention in which the outer race, in ball and roller bearings, or sleeve, in a plain bearing is mounted in an outer or second bearing in such a way that the second bearing can be driven by separate means at a speed approximately double the speed equal to that produced by the cloth over the roll, then the back drag on the conventional fixed bearing will exactly balance the forward drag of the driven second bearing.

The result will be a roll with Zero effective drag provided the bearings are of equal characteristics. This result will be independent of the load imposed on the roll. The result would eliminate all bearing friction in the multiple roll set-up and leave only the liquid to cloth, liquid to roll or air to cloth friction.

In a tank in which some rolls are above and others below the level of the liquid, the lower rolls may be in conventional fixed bearings and, for the upper rolls, both ends may have the outer races, or second bearings, driven so the forward drag of the upper rolls would balance the back drag of the lower rolls and all, or part, of the liquid or air frictions.

A further improvement of this invention is to povide lower rolls constructed with a specific gravity close to that of the liquid; the buoyancy and flotation effect minimizing bearing load.

There are many applications where such a frictionless roll or shaft can be used. Multiple, vertical pass web dryers over rolls are an example, wherein one set of draw rolls on the exit end of the machine are enabled to pull fabric over many rolls without tension build-up by using the novel dragless or torqueless roll of this invention.

The principal object of the invention is therefore to provide an apparatus for tension-free treatment of an elongated web, drawn through a treatment zone supported on a plurality of rolls, the web being free of mechanical stress regardless of the number of rolls, by eliminating the build-up of roll bearing friction while impositively urging the rolls in the desired angular direction, and being able to balance out frictions of the rolls and web in their fluid environment.

Another object of the invention is to provide a machine for handling an elongated moving web, festooned in loops on rolls, wherein the rolls are jouralled in bearings and at least one bearing of at least one roll is power rotated to compensate for bearing drag.

A further object of the invention is to provide such a machine in which certain of the rolls are submerged in a liquid tank and the submerged rolls are each provided with predetermined buoyancy and floatation to substantially compensate for upward pull of the web and counter balance such pull with a predetermined equal gravitational force exerted by the roll in its bearings.

Other objects and advantages of the apparatus of the invention will be apparent from the claims, the description of the drawings and from the drawings in which:

FIGURE 1 is an end elevation of a roll constructed in accordance with the invention, in half section.

FIGURE 2 is a similar view showing a double bearing :and drive at each opposite end of the roll.

FIGURE 3 is an end elevation, in section on line 3-3 of FIGURE 7 of a typical machine, such as a textile dyer or washer, constructed in accordance with the invention.

FIGURE 4 is a fragmentary detail view similar to FIGURES 1 and 2, showing another embodiment of the driven double bearing of the invention.

FIGURE 5 is a view similar to FIGURE 4 of still another embodiment of the invention.

FIGURE 6 is a diagrammatic side elevation of one of the submerged, hollow, lower rolls of the machine shown in FIGURES 3 and 7.

FIGURE 7 is a side elevation of the machine shown in FIGURE 3, and

FIGURE 8 is a view similar to FIGURE 7 showing the invention incorporated in a typical festoon type web dryer.

As shown in FIGURES 3 and 7, designates a typical machine, such as a continuous washer, for washing fabrics, such as the elongated web 21. Such machines usually consist of a series of tanks, or tubs, 22, 23 and 24, each having a series of upper, or top, rolls 25, 26 and 27 and a series of lower, or bottom, rolls 28, 29, 30 and 31. A guide, or expander, roll 32 is also provided. The tanks 22, 23 and 24 are separated by a pair of squeeze rolls, such as 33 and 34 or 35 and 36, the nip of the rolls squeezing out some of the liquid onto a suitable trough 37 prior to entering the succeeding tank. Conventionally, the control of the fabric web 21, as it advances through the machine, is achieved by a swinging compensating roll, or pivot type dance roll, 38. conventionally also the rolls 25, 26, 27, 28, 29, 30 and 31, which support and guide the web 21 in looped, or festooned configuration, are not driven and, therefore, any tension which accumulates due to passage of the fabric web through the treatment zone 39 of the machine 20, will multiply and build up during passage over and under the rolls. Disregarding web to air and web to liquid friction, which is negligible at customary speeds the accumulation of tension, or mechanical stress, in the web 21 is principally due to friction in the bearings of the rolls, increasing progressively, roll to roll, from entrance to exit of the treatment zone 39.

While it has heretofore been proposed to positively drive the submerged rolls, as in the above mentioned Patent 2,474,717 to Belcher, to equalize tension, the overspeed of such rolls results in slippage which may damage the fabric and creates mechanical stress to counter mechanical stress thereby compounding tensions.

In this invention, positive drive to the supporting and guiding surface of the submerged rollers is avoided, and the applying of a sliding, or slipping force to the inner loops of the fabric web sufficient to frictionally increase the speed of the moving web is also avoided. Instead, this invention contemplates that the roller surface travel at exactly the speed of the moving web, to accompany and support the web without relative friction or scuffing, but that the rollers exert no drag on the web such as is caused by conventional fixed bearings. It will be understood that conventionally the upper rolls of devices of this type include journals at each opposite end thereof rotatable in bearing blocks fixed to the frame and that the lower rolls, if submerged, have their journals rotatable in similar fixed bearings, or fixed stuffing boxes.

As shown in FIGURE 1, each roll such as of this invention may have the journal 42, at one end thereof, rotatable in a journal bearing 43 fixed by bolts 44 to the tank 23. However, the journal 45, at the other end thereof, is mounted in a first journal bearing 46, and the journal bearing 46 is itself rotatable in a second bearing 47. As shown, the first bearing 46 may be of the hollow sleeve type with a metal bushing 48 and the second bearing 47 may, conveniently, consist of two bearing blocks 49 and 50 but any suitable type of ball, roller or other anti-friction bearing means may be used. Thus the rotatable means 52 of the invention which may consist of any desired number of rolls, or equivalent elements, each having a web supporting surface such as 53 rotatable about an axis 54, and each having journal means such as a shaft, spindle gudgeon or the like, is provided with at least one double bearing '55 such as 46 and 47 at at least one end of at least one roll. Preferably, however, a double bearing is provided at each opposite end of each roll as shown in FIGURE 2, the double bearing 56 being identical with the double bearing 55.

Drive means 60 includes a suitable sprocket, or gear, 61 fast to the rotatably mounted outer race, or sleeve, 46 of each double bearing 55 or 56 so that it is operably connected to rotate the second journal bearing of the double bearing. As shown in FIGURE 7, in dotted lines, the power train includes the chain 62 trained on the sprockets 61, 63 and 64 of the second journal bearings of each upper roll 25, 26 and 27 and around the sprocket 65 of a variable speed unit of well known type. The web advancing means 66, consisting of the conventional driven squeeze rolls 35 and 36 drives the variable speed unit 70 by chain 67 and sprockets 68 and 69, or the web advancing means 66 and the bearing drive means 60 may be operably synchronized in any other convenient manner. The submerged, or lower rolls 28, 29, 30 and 31 are similarly equipped with double bearings at at least one end thereof, each including a sprocket for rotating the first bearing in the second bearing, the sprockets being operably connected to the variable speed unit 70 by a suitable power train, shown in dotted lines, and designated generally as 71, although if both ends of the top rolls have double bearings, the lower rolls may have single bearings.

The variable speed unit 70 enables the outer bearing races of the various rolls to be rotated to increase, or decrease, the rotational speed thereof relative to the surface speed of the web advancing rolls 35 and 36. As indicated generally at 72, it is also conventional, when the machine 20 includes a plurality of tanks 22, 23 and 24, and the squeeze rolls such as 35 and 36 have a positive nip for advancing the web 21, to tie in the drive of each dance roll 38 with its squeeze rolls by means of variable speed unit 70. Tension may thus be controlled on the web 21 by the amount of counterbalancing weight used on the pivoted dance roll 38 so that tension may be varied to the amount needed.

The drive means 60 is preferably so arranged that it rotates the second, or outer, bearings 47 at least at the same speed as the speed of the web to eliminate bearing drag and preferably at a slightly greater speed in order to impositively exert a slight pull on the fabric in the direction of advance.

It will be noted that in textile washers the lower rolls may be submerged below the level 74 of the liquid 75 in the tanks 22, 23 and 24 and that it may also be desirable in some installations for both the upper and the lower rolls to be submerged.

In this invention, the rolls 28, 29, 30 and 31, are of predetermined buoyancy and flotation, depending on the roll dimensions and the particular liquid used. For example, if the liquid 75 is water, each roll such as 28, is preferably hollow as at 76, and of such weight and volume as to float with a weight of substantially zero on the roll bearings. Thus there is substantially no gravitational load on the bearings of the submerged rolls. The term substantially is used because it has been found desirable to have a very slight amount of tension, or downward pull on the loop of fabric in which the submerged roll is located. Thus each roll 28, 29, 30 and 31 is constructed to have a predetermined weight of, for example, one pound in water, to thereby exert a pull of one half pound tension on each of the two stretches such as 77 and 78 of web fabric forming a depending loop 79. (FIG. 6.) Stretches 77 and 78 therefore exactly counterbalance the negligible weight of the roll and allow the roll to be weightless as far as the load on the bearings is concerned. As shown in FIGURE 3, one hearing at one end of each submerged roll such as 29 may be journalled in a fixed bearing 81 and this bearing need not bea perfect fit since slight play is desirable in view of the weightlessness of the roll. The journal 82 at the other end of each submerged roll may extend through suitable stuffing boxes 83 in the wall 84 of the tank, and be provided with a driven double bearing 85 as described above. In the case of upper rolls which are submerged, each upper roll is sufficiently buoyant in the liquid to be substantially weightless but is arranged to have an upward flotation force of about one pound in Water to exert a slight upward pull on the loop passing thereover.

In FIGURE 4 another embodiment of the driven double bearing of the invention is disclosed wherein a fixed stub shaft 86 is co-axial with the journal 87 and both are encircled by a sleeve bearing 88 having a sprocket 89 fast thereto.

In FIGURE 5 another embodiment of the driven double bearing is shown in which the roll 90 is hollow and rotatable on ball bearings 91 and 92 around a central shaft 93, the bearings 91 and 92 being pressed into the ends of the rollow roll. The shaft 93 is in turn freely rotatable in a pair of bearing blocks 94 and 95 of the ball bearing type. A sprocket 96 is fast to the shaft 93 for driving the shaft.

In FIGURE 8, the invention is shown applied to a typical dryer 100 of the multi-pass, festoon, or depending loop, type. The enclosure '101 is an oven, heated by any convenient means such as steam coils 102 and there are a series of upper rolls such as 103 and a series of staggered, lower, rolls 104. The elongated continuous web 105 is drawn through the dryer by the nip rolls 106 and 107 forming the Web advancing means 108. Preferably at least one end of each of the upper and lower rolls is Supported in a double bearing such as 110 or 111, identical with double bearings 55, 56 and 85, all on the same side and driven by drive means 112 operably connected to the means 108 by a suitably power train 113 including a variable speed unit 114.

The apparatus of this invention may be used advantageously with yarn and top or other relatively weak materials to control tension and avoid build-up of bearing friction in a set of support and guide rolls. It is of course possible to mount each roll by means of ball bearing races or the like on a through shaft and to then rotate the through shaft to impositively urge the roll in the desired angular direction of rotation.

The major factors contributing to torque in a bearing are believed to be the design, finish and materials of the bearing, the rolling, or other friction, caused by the imposed load and the viscous drag caused by the lubricant. There is a starting torque and a running torque but it is believed that for all practical purposes increase in the torque is substantially less at normal velocities than the increase in rotational speed unless and until terminal velocity causes a crushing centrifugal force on the hearing. Since the normal range of rotational velocities, of the rolls used in machines constructed in accordance with this invention, is known and since the bearing torques are relatively constant at such speeds, the second bearings can be rotated at such speeds as to overcome and compensate for such torque during operation. However, by reason of the speed control mechanism in the drive, any such changes can of course be quickly compensated.

We claim:

1. In apparatus of the type having a plurality of upper and lower rolls for supporting a moving web in a looped path, each said roll having journal means at each opposite end thereof, the combination of:

a first journal bearing on said apparatus, at each end of each said roll, supporting the journal of each said roll for free rotation;

a second journal bearing on said apparatus, supporting at least one said first journal bearing at at least one end of one said roll, for free rotation and drive means on said apparatus, including a variable speed control mechanism for rotating said first journal bearing at a predetermined speed,

whereby at least said one roll may be impositively urged to rotate in the direction of travel of said moving web to compensate for shrinkage thereof without mechanical stress on said web.

2. A substantially frictionless roll for supporting and guiding an elongated web, said roll having:

at least one double journal bearing, including a first hearing supporting said roll for free rotation, and a second bearing supporting said first bearing for free rotation, and

variable speed control drive means for rotating the said first bearing of said double bearing to control bearing friction and drag on said roll.

3. A machine for treatment of an elongated web of material, said machine comprising:

a plurality of rolls rotatably mounted on said machine to extend transversely thereof for supporting said web in the form of at least one depending loop;

web drive means associated with said machine for advancing said web therethrough at a predetermined speed while supported, and guided, on said rolls;

a plurality of first bearings on said machine, each supporting at least one end of one of said rolls for free rotation;

a plurality of second bearings on said machine, each second bearing supporting one of said first bearings for free rotation, and

bearing drive means including variable speed control mechanism operably connected to said first bearings to drive said first :bearings at a selected predetermined speed adapted to impositively urge said rolls to rotate at a surface speed slightly greater than the speed of advance of said web whereby bearing friction and drag on said rolls is compensated and a slight pull is exerted on said web in the direction of web advance.

4. Apparatus for supporting and guiding an elongated web during treatment in a liquid immersion tank having a predetermined liquid level therein, without imparting damaging longitudinal mechanical stresses thereto, said apparatus comprising:

web advancing means rfor moving said elongated web longitudinally, at a predetermined linear speed, through said immersion tank;

rotatable means including at least one hollow roll submerged below the said liquid level in said tank for guiding said web, said roll being adapted to substantially float in said liquid to reduce frictional drag on said web and having an axis of rotation;

first bearings rotatably supporting each said rotatable means for free rotation about said axis;

second bearings rotatably supporting each said first bearing for free rotation about said axis, and

drive means, operably connected to each said first bearirrg and rotating the same at a predetermined speed relative to the speed of said web to control bearing friction of said roll.

5. Apparatus as specified in claim 4 wherein:

said rotatable means includes at least two upper rolls normally above the said liquid level in said tank,

at least one end of each said upper roll being supported in one of said first and second bearings with the said first bearings rotated by said drive means,

whereby said rolls offer minimum bearing resistance and drag to said web.

6. Apparatus for transporting elongated, flexible sheet material through a liquid immersion tank without imparting damaging longitudinal stresses to said material, said apparatus comprising:

a plurality of upper and lower bearing supported, freely-revoluble rolls extending transversely of said tank at spaced heights therewithin, at least some of said rolls being submerger below the normal liquid level of said tank;

material advancing means for pulling said material, in a path looping under said lower rolls and looping over said upper rolls, through said tank, at a predetermined linear speed;

bearing drag, compensation means, associated with the bearings supporting said rolls for reducing the bearing drag of said rolls substantially to zero;

each said submerged roll being of predetermined displacement, volume, flotation structure and flotation material to substantially float with a predetermined buoyancy in said liquid,

thereby reducing frictional bearing drag on said material substantially to zero.

7. Apparatus as specified in claim 6 wherein:

said submerged rolls include at least two upper rolls and at least one lower roll;

said upper rolls each being of predetermined buoyancy and flotation and said lower roll being of predetermined buoyancy and flotation different from that of said upper rolls;

whereby said upper and lower rolls have a differential buoyancy corresponding to their respective bearing loads.

8. Apparatus as specified in claim 7 wherein:

each said submerged lower roll has a predetermined weight of approximately one pound when below the level of the liquid in said tank to exert a slight downward pull on the loop of material passing thereunder,

and each said submerged upper roll has a predetermined upward flotation force of about one pound when below the level of the liquid in said tank to exert a slight upward pull on the loop of material passing thereover.

9. Apparatus as specified in claim 6 wherein:

said bearing drag compensation means comprises double bearings, each including a first bearing, supporting each said roll for free rotation, and rotatable in a second bearing, and

variable speed control drive means rotating said first bearing of each said double bearing at a predetermined speed for urging each said roll impositively to rotate at a surface speed slightly greater than the speed of advance of said material.

References Cited UNITED STATES PATENTS 410,279 9/1889 Hey-wood. 1,459,454 6/ 1923 Trotter. 1,600,071 9/ 1926 Shaifer. 1,873,740 8/1932 Crick 68--l80 2,027,451 1/1936 Rooney et al 226-194 X FOREIGN PATENTS 432,094 7/ 1935 Great Britain.

WILLIAM L. PRICE, Primary Examiner.

I. BUNEVICH, Assistant Examiner. 

